Phycology Section, Patrick Center for Environmental Research, Academy of Natural Sciences of Drexel University. Closterium gracile var. elongatum (NADED 316098). https://diatom.ansp.org/taxaservice/ShowTaxon1.ashx?naded_id=316098. Accessed 19 Mar 2018. This web service reports all information about a given algae taxon available at the time of retrieval.